The NZ Metal Roof and Wall Cladding Code of Practice is a comprehensive design & installation guide, and a recognised related document for Acceptable Solution E2/AS1 of the NZ Building Code.
This section sets out the testing methodology to evaluate the structural performance of sheet roof and wall cladding systems. Structural Testing covers uniformly distributed load (UDL) and concentrated (point load). These procedures apply to all metals and plastic sheeting.
The UDL test simulates wind uplift by subjecting test specimens to pressure from underneath.
UDL testing is typically carried out to simulate outward loads, where material is restrained by fasteners (or clips) at intermittent points; rather than inward loads where material is retrained linearly by purlins or girts. Even with asymmetrical trapezoidal profiles, failure adjacent to the fastener from the imposition of outward loads is inevitably cause of failure in typical applications.
Testing for inward load can also be conducted, if required.